Audio-files won't play after being converted to Podcasts.

[Jokerstyle]

Hello, I'll keep this as short as possible so as not to bore you.

I have a bunch of regular mp3-files that I want to listen to as a podcast, due to auto-resume and whatnot.

If I add them to my iPhone they play just fine while being under the standard "Music" category.
When I change their media type to podcast, the files are turned "invisible" in iTunes, meaning they can be found in my iPhones podcast section, but cannot be found through iTunes any longer.

Now, my newly converted audio files won't play when I open them through the podcast section on my iPhone.
I click the file, the regular "Playing your file"-window appears for a split second and then I'm thrown back into my list of podcasts.

So in short, I can play the files through my phone while they're still listed as "Music", but when I list them as "Podcasts" my phone no longer plays them.

What I have tried:
1: Creating an AAC version of the files through iTunes and doing the same thing.
2: Opening the mp3-files in Audacity and re-exporting them.
3: Downloading "MP3tag" and adding the extended tags "ITUNESPODCAST = 1" and "ITUNESPODCASTURL = www.google.com"

The thing that really bugs me is that I ALREADY got it working once upon a time. I've had the first twelve mp3-files in my podcast category for a year or so fully working, but I decided I wanted to add the rest of the files today. That's when I remembered I had to work some magic to get it working last time, but now I have no idea what "1 year ago"-me did that I can't reiterate now.
The only thing I can remember is that step 3 seemed to be involved in my process.

 

[Jokerstyle]

Just wanted to let people know that I'm still looking for help on this issue. Has anyone heard of anything like it?

Additional info:
The Mp3's exist on my local harddrive. I first add them to iTunes, and from the iTunes library add them to my phone. I can play the files with iTunes on my computer without hassle.
On the phone the files still won't work when being played through the podcast program, but work fine if I let them remain in the "Songs" folder. Without the advantages of a podcast, however.

I have since tried to use other programs, namely "Audible" and "Audiobooks". They won't play the files but will play my other "regular" podcasts without problem.